(CNN) -- Retired U.S. Gen. Wesley Clark, a supporter of Democratic presidential candidate Barack Obama, on Sunday questioned whether Sen. John McCain's military experience qualified him to be commander-in-chief.

Retired Gen. Wesley Clark, who ran for president in 2004, questioned John McCain's qualifications Sunday.

The McCain campaign called for Obama to condemn the remarks.

The dust-up began with Clark's appearance Sunday on CBS' "Face the Nation," where moderator Bob Schieffer asked him about his interview with the Huffington Post earlier this month.

In the interview, Clark said McCain, the presumptive Republican nominee, was "untested and untried."

When Schieffer asked to explain the comment, Clark said he was referring to McCain's experience, or lack thereof, in setting national security policies and understanding the risk involved in such matters.

"I certainly honor his service as a prisoner of war. He was a hero to me and to hundreds of thousands and millions of others in the armed forces, as a prisoner of war. And he has traveled all over the world. But he hasn't held executive responsibility," said Clark, a former NATO commander who campaigned for the Democratic presidential nomination in 2004.

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"He hasn't been there and ordered the bombs to fall. He hasn't seen what it's like when diplomats come in and say, I don't know whether we're going to be able to get this point through or not," Clark said.

Schieffer noted that Obama did not have any of those experiences, nor had he "ridden in a fighter plane and gotten shot down."

"Well, I don't think riding in a fighter plane and getting shot down is a qualification to be president," Clark said.